linux-vybrid_public/Documentation/ABI/testing/sysfs-block

What:		/sys/block/<disk>/stat
Date:		February 2008
Contact:	Jerome Marchand <jmarchan@redhat.com>
Description:
		The /sys/block/<disk>/stat files displays the I/O
		statistics of disk <disk>. They contain 11 fields:
		 1 - reads completed succesfully
		 2 - reads merged
		 3 - sectors read
		 4 - time spent reading (ms)
		 5 - writes completed
		 6 - writes merged
		 7 - sectors written
		 8 - time spent writing (ms)
		 9 - I/Os currently in progress
		10 - time spent doing I/Os (ms)
		11 - weighted time spent doing I/Os (ms)
		For more details refer Documentation/iostats.txt


What:		/sys/block/<disk>/<part>/stat
Date:		February 2008
Contact:	Jerome Marchand <jmarchan@redhat.com>
Description:
		The /sys/block/<disk>/<part>/stat files display the
		I/O statistics of partition <part>. The format is the
		same as the above-written /sys/block/<disk>/stat
		format.


What:		/sys/block/<disk>/integrity/format
Date:		June 2008
Contact:	Martin K. Petersen <martin.petersen@oracle.com>
Description:
		Metadata format for integrity capable block device.
		E.g. T10-DIF-TYPE1-CRC.


What:		/sys/block/<disk>/integrity/read_verify
Date:		June 2008
Contact:	Martin K. Petersen <martin.petersen@oracle.com>
Description:
		Indicates whether the block layer should verify the
		integrity of read requests serviced by devices that
		support sending integrity metadata.


What:		/sys/block/<disk>/integrity/tag_size
Date:		June 2008
Contact:	Martin K. Petersen <martin.petersen@oracle.com>
Description:
		Number of bytes of integrity tag space available per
		512 bytes of data.


What:		/sys/block/<disk>/integrity/write_generate
Date:		June 2008
Contact:	Martin K. Petersen <martin.petersen@oracle.com>
Description:
		Indicates whether the block layer should automatically
		generate checksums for write requests bound for
		devices that support receiving integrity metadata.

What:		/sys/block/<disk>/alignment_offset
Date:		April 2009
Contact:	Martin K. Petersen <martin.petersen@oracle.com>
Description:
		Storage devices may report a physical block size that is
		bigger than the logical block size (for instance a drive
		with 4KB physical sectors exposing 512-byte logical
		blocks to the operating system).  This parameter
		indicates how many bytes the beginning of the device is
		offset from the disk's natural alignment.

What:		/sys/block/<disk>/<partition>/alignment_offset
Date:		April 2009
Contact:	Martin K. Petersen <martin.petersen@oracle.com>
Description:
		Storage devices may report a physical block size that is
		bigger than the logical block size (for instance a drive
		with 4KB physical sectors exposing 512-byte logical
		blocks to the operating system).  This parameter
		indicates how many bytes the beginning of the partition
		is offset from the disk's natural alignment.

What:		/sys/block/<disk>/queue/logical_block_size
Date:		May 2009
Contact:	Martin K. Petersen <martin.petersen@oracle.com>
Description:
		This is the smallest unit the storage device can
		address.  It is typically 512 bytes.

What:		/sys/block/<disk>/queue/physical_block_size
Date:		May 2009
Contact:	Martin K. Petersen <martin.petersen@oracle.com>
Description:
		This is the smallest unit the storage device can write
		without resorting to read-modify-write operation.  It is
		usually the same as the logical block size but may be
		bigger.  One example is SATA drives with 4KB sectors
		that expose a 512-byte logical block size to the
		operating system.

What:		/sys/block/<disk>/queue/minimum_io_size
Date:		April 2009
Contact:	Martin K. Petersen <martin.petersen@oracle.com>
Description:
		Storage devices may report a preferred minimum I/O size,
		which is the smallest request the device can perform
		without incurring a read-modify-write penalty.  For disk
		drives this is often the physical block size.  For RAID
		arrays it is often the stripe chunk size.

What:		/sys/block/<disk>/queue/optimal_io_size
Date:		April 2009
Contact:	Martin K. Petersen <martin.petersen@oracle.com>
Description:
		Storage devices may report an optimal I/O size, which is
		the device's preferred unit of receiving I/O.  This is
		rarely reported for disk drives.  For RAID devices it is
		usually the stripe width or the internal block size.